溶胶–凝胶封孔处理后AZ91D镁合金微弧氧化膜的耐蚀性

Corrosion resistance of sol-gel sealed micro-arc oxidation coating on AZ91D magnesium alloy

以正硅酸乙酯(TEOS)为前躯体,采用溶胶–凝胶技术在微弧氧化处理的AZ91D镁合金基体表面制备了SiO2封孔涂层。采用热重(TG)、能谱(EDS)和扫描电镜(SEM)对凝胶热性能和涂层的成分及微观形貌进行了分析,并对封孔处理前后的试样进行耐蚀性检测。结果表明,封孔处理后,镁合金耐0.1 mol/L硫酸的时间超过50 min,在质量分数为3.5%的NaCl溶液中的自腐蚀电位正移了50 mV左右,自腐蚀电流密度降低了一个数量级,表现出良好的耐蚀性。

A seal coating was prepared on micro-arc oxidized AZ91D magnesium alloy substrate by sol–gel technique using tetraethyl orthosilicate as precursor.The thermal properties of xerogel,composition and morphology of the seal coating were characterized by thermogravimetry（TG）,energy-dispersive X-ray spectroscopy（EDS） and scanning electron microscopy（SEM）,respectively.The corrosion resistance of the micro-arc oxidized and the sealed magnesium alloy substrate were studied.The results showed that the sealed magnesium alloy endured over 50 min in a 0.1 mol/L H2SO4 solution,and had a self-corrosion potential shifted positively by 50 mV as well as a self-corrosion current density decreased by an order of magnitude in a 3.5wt% NaCl solution,showing good corrosion resistance.